Class A has 8 pupils and class B has 10 pupils. Both classes sit the same maths test. The mean sco

[math_celebrity]

Class A has 8 pupils and class B has 10 pupils. Both classes sit the same maths test. The mean score for class A is 55. The mean score for both classes is 76. What is the mean score (rounded to 1 DP) in the maths test for class B

Mean of the sum equals the sum of the means.

U(A + B) = U(A) + U(B)
76 = 55 + U(B)

Subtract 55 from each side, we get:
U(B) = 21